Vehicle-lifting jacks



United States Patent Alexander Hahn 1, Waldhohlweg, Schneidhain, uber Konigstein (Taunus), Germany Appl. No. 688,114 1 Filed Dec. 5,1967

Inventor Patented Dec. 29, 1970 Priority Dec. 5, 1966 Germany No. 1162010 VEHlCLE-LIFIING JACKS 3 Claims, 2 Drawing Figs.

US. Cl... 254/1 Int. Cl B661" 3/02 Field of Search 25 4/1 95; 248/125, 412; 24/1262, 263SW, 263.5RB; 269/ 1 66, 217

[56] References Cited UNITED STATES PATENTS 2,595,008 4/1952 Sill 24/126.2UX FOREIGN PATENTS 1,941,462 6/1966 Germany t 254/1 18,007 12/1887 Great Britain, 248/125 Primary Examinen-Theron E. Condon Assistant Examiner-David R. Melton Atmrhey-Ostrolenk. F aber. Gerb and Soffen ABSTRACT: The specification describes an improved vehicle jack having a pinion with sharp teeth arranged to bite into a stationary upright part of the jack and thus save machining teeth in the upright part.

' PATENTEU nEczslg m Fig. 2

VEHICLE-LI FIIN G J ACKS The invention relates to vehicle lifting jacks of the type comprising an upright column of constant cross section, a carriage arranged to move up and down column, and a drive roller engaging the column.

Known jacks of this type have a column with rack teeth with which the roller, which is provided with spur gear teeth, meshes. The roller or geared wheel is provided with a pawl to prevent it running backwards.

Such known forms of jack with a rack drive have the disadvantage that the conjugate gear wheel and rack teeth have to be made with a relatively high degree of precision and are therefore expensive. Furthermore good lubrication is necessary.

One object of the present invention is to avoid the disadvantages of prior-art jacks. i

Another object of the present invention is to provide a jack which is simple and cheap to produce.

A still further object of the invention is to provide a jack which can be used continuously for raising and lifting loads and is reliable in use.

With these and other objects in view the present invention provides a vehicle-lifting jack comprising an upright column, a carriage arranged for running up and down the column, a drive roller which is retained in position by the carriage and is arranged to rotate about a substantially horizontal axis, the carriage having oblique faces so as to press the roller against the column, projections on the peripheryof the roller which are harder than the column and adapted to bite into it when the jack is under load and the roller is turned and form-corresponding recesses with which the projections can mesh in later use.

Owing to the use of the projections which are harder than i the column, machining of the column to produce meshing recesses and teeth is not necessary. Despite the simplicity of construction reliable operation is ensured since the higher the load which the jack has to support the greater the pressure between the cooperating surfaces of the roller and the column and therefore the firmer the engagement.

One embodiment of the invention is nowdescribed with reference to the accompanying drawing.

FIG. 1 shows a vertical section and side view of the jack in accordance with the invention.

FIG. 2 shows a horizontal section on the line II-Il in accordance with FIG. 1.

The jack comprises a bottom plate la on which there is welded an upright column 1 which is in the form of a metal bar such as a rolled or extruded T-section girder. A carriage or slide 2, suitably adapted to correspond to the column 1 moves up and down it. The carriage 2 has two oppositely placed walls which project beyond the column to the side and has openings or windows 2a with oblique running surfaces 3a which are parallel to each other and in an upward direction run towards the column. In these openings 2a the carriage carries a drive roller 4 in the form of a pin on which two guide collars 4a and 4b are arranged at such a distance apart, see FIG. 2, that they lie against the sides of the transverse web of the column so that the movement of the roller or pin along its axis is prevented.

An end of the roller projecting out of the carriage 2 carries an eye 5 into which a Tommy bar or a crank can be fitted for manual turning of the roller. The roller or pin has smooth end journals 6 and 6a which run against the oblique surfaces 3. In the central section between the collars 4a, 4b the roller has helical teeth 9 which bite into the column 1 when the drive roller is turned under load. Instead of having teeth as shown, the roller can be knurled. The toothed. surface of the roller is made harder than the part of the column it is to engage. For raising the load the carriage carries an abutment 8 which engages a specially provided abutment on ,the vehicle to be lifted.

Owing to the fact that the first time the jack is used the teeth 9 bite corresponding recesses in the column 1, a positive engafiement is obtained which prevents an sliding of the drive ro er along the column. The angle the ob ique faces'3 make to the column is so chosen that the jack is self-locking owing to the friction created. The frictional locking effect between the journals 6a, 6b of the roller 4 and the oblique faces 3 of the carriage is overcome as soon as the roller is turned in the lifting direction or in the lowering direction, but becomes immediately effective again as soon as the manually applied torque is released. The roller 4 is continuously pressed upwards by a spring 7.

Iclaim:

1. A vehicle-lifting jack comprising an upright column, a carriage arranged for running up and down the column, a drive roller which is retained in position by the carriage and is arranged to rotate about a substantially horizontal axis, the carriage having oblique faces so as to press the roller against the column, the column being formed of a material having a first hardness, projections on the periphery of the roller which are formed of a material which is hard-er than the material of which the column is formed, and which projections are adapted to bite into the column when the jack is under load and the roller is turned, and the projections-form corresponding recesses in the column with which the projections can mesh in later use, and a spring connected with the carriage and pressing the roller in an upper direction against the column to ensure a positive and continuous interengagement between the projections and the meshing recesses formed on the column.

2. A jack according to claim 1 in which the column is a piece of T-section girder.

3. A jack according to claim I including locking means for locking the carriage in position along the column. 

